Two-cycle engine



:s sheets-shea 1 I Q QQ m Q l QQ QQQQ QQ QQQQQQQQ n l w Y l I QQQQQ QINI/EN TOR .Pony/m (wz 70N lv HHIHHHHMIMHH- nl. um www QN TWO-CYCLEENGINE Filed June 8, 1931 lll March 13 March 13, 1934. R. CHILTONTWO-CYCLE ENGINE sheets-sheet 2 A Filed June 8.v 1931 m VENTO/ lRozHNDCHILTQN R. CHILTON March 13, 1934.

TWO

-CYCLE ENGINE Filed June 8, 1931 3 Sheets-Sheet 3 Patented Mar. 13, 1934PATENT oFFlcl.A

TWO-CYCLE ENGINE Boland Chilton, Ridgewood, N. J., assignor to WrightAeronautical Corporation, a corporation of New York Application June s,1931, serial No. 542,898 4 claims. (o1. 12a-s3) This invention relatesto the type of two cycleengine wherein adjacent cylinders are united inpairs by common combustion chambers, one cylinder of each pair beingprovided with inlet ports 5 and the other with exhaust ports, the portsbeing over-run by the pistons to control the admission to and emissionfrom the engine of -the fuel charges and burnt gases, respectively.

In engines of the above class it is desirable that both the exhaustopening and closing precede the corresponding events at the inlet ports,for which purpose out-of-phase pistons, with the pistons in the exhaustcylinder leading, are desired. This permits supercharging and preventsloss of charge thru the exhaust ports. Such outof-phase pistonrequirement further complicates the problem of obtaining good balancewhich is already a diiiculty from the fact that two pistons may notreach dead center together without also being fired simultaneouslywhereby the chief advantage of the two cycle-engine would be lost. (Infour cycle-engines it is desirable to have one piston on its ring deadcenter and one piston on its exhaust dead center simultaneously whichconforms to the requirements for balance with conventional cylinderdispositions).

Opposed pistons with dual crankshafts geared together, and pairedcylinders L'disposed in two banks over a common crankshaft, are amongthe expedients that have been used in two cycle constructions, but theformer gives a relatively bulky engine and the latter does not give goodbalance with even firing intervals and has involved bent connecting rodsin the effort to keep'the top of the cylinders close together to avoidexcessive length of the cylinder joining combustion chambers There is aform of engine, however, `having the cylinders arranged aroundand'parallel to the power shaft. By importing the paired cylinderarrangement into such a cylinder disposition the present inventionachieves the desired out-ofphase piston motion in an extremely compactengine which may be accurately balancedand which has evenly spaced ringimpulses. The preferred embodiment comprises double ended pistons .inaligned cylinders giving an engine with combustion chambers at each end.

When an even number of cylinder pairs is used, then, for equal spacingof the-firing impulses on two cycle operation, the'cylinders of one end,are paired by common combustion chambers in staggered relation to thecombustion chambers pairing the cylinders of the other end. On the otherhand, even ring impulses are obtained with the common combustionchambers at one end opposite those at the other end in the case where anodd number of pairs used, and this is the preferred embodiment becauseit permits of unsymmetrical circumferential spacing of the cylinderswhich would give odd lengths to the connecting combustion chambers inthe case of the staggered arrangement.

The close spacing of the cylinders of each pair as compared to the anglebetween the cylinders of adjacent pairs permits a desirable reduction inthe out-of-phase angle between the pistons of each pair which gives thedesired timing for the ports. The increased space between adjacent pairsaffords room for the intake and exhaust 70. pipes which may thus bedisposed within the general overall diameter of the cylinders wherebythe outside dimensions of the engine are reduced, thus contributing tothe extreme compactness which is one of the objects of this invention,which is here illustrated as an. aircraft power plant wherein minimumdiameter is of great importance.

In the drawings, wherein like reference characters denote like orcorresponding parts,

Fig. 1 is alongitudinal section on the line 1-1 of Fig. 2;

Fig. 2 is an end view in part section on the line 2-2 of Fig. 3, and iFig. .3 is an inverted plan view in section on the line 3-3 of Fig. 2.

Referring first to Fig. 1, the main engine body is divided into frontand rear jacketed combustion chamber sections 10 and 12 secured vtointermediate jacketed sections` 14 and 16 and provided 90 with cylinderliners 18a and 18h. .These liners or sleeves 18a and 18b"are providedwith ports, the preferred construction of which is fully described in myco-pending application Serial No.

p 525,494- led March 26,1931 and does not form4 95 a part of the presentinvention, the cylinder disposition of which may be practiced with anysuitable cylinder construction. Supported on bearings 20 in the mainengine body is the power shaft 22 having an angular crankpin 24 on which100 is mounted thespider 28 on the ball bearings 30. The preferredconstruction of the angular crank mechanism is described in detail in myco-pending applicati/on Serial No. 532,552 illed April 24,

1931 and is not a part of the present invention,

struction for which forms the subject matter of said co-pendingapplication Serial No. 532,552 led April 24, 1931 and is not a part vofthe present invention with which other piston driving connections may beused. f

Referring to Fig. 2 and considering that the direction of rotation ofthe power shaft 22 is clockwise the sleeve 18a will comprise an exhaustcylinder and the sleeve 18b an inlet cylinder and these are united toconstitute a pair by the common combustion chambers 36 (Figs. 1 and 3).It will be seen that, with any form of angular crank or wabble platemechanism, each piston arrives at its dead center position when theplane of the angular crank is radial to the particular cylinder, andthat, (referred to crank angles) the exhaust piston in the sleeve 18awill lead the inle piston in the sleeve 18h by the angle whichl thesecylinders subtend from the center of the engine.

Connected to the collecting belt around the inlet ports 18h is an inletpipe 38 and similarly connected'to the belt around the exhaust ports 18ais the exhaust pipe 40. This disposition is repeated at the other pairsof cylinders, the specic showing of the drawings illustrating threepairs of cylinders at either end of the engine.

The point of maximum eiective displacement of the two out-of-phasepistons in any pair of cylinders is when the plane of the angular crankis midway between those cylinders and this is the instant of ignitionwhereby the power impulses from one end of an engine with three pairs ofcylinders will be spaced at 120 apart, the impulses at the other endoccurring at the intermediate points 60 from those of the rst end, dueto the fact that opposed pistons reach the outer end of their strokes,180 apart, and herein will be seen the reason for using an odd numberof pairs of cylinders in the case where the common combustion chambersat the front and back of the engine are disposed one opposite to theother. This disposition thus gives evenly spaced ring impulses althoughthe individual cylinders are not evenly spaced and it will be seen thatthis uneven spacing affords room for the exhaust pipes 40 and inletpipes 38 within the general.

overall diameter of the engine which is thus unusually compact.

Referring now to Figure 3 which shows one pair of cylinders in section,withthe piston of the rear inlet cylinder at its outer dead center, theout-of-phase of the pistons is illustrated so that it may be seen thatthe exhaust ports will be opened and closed before the inlet ports. Inthis gure it is also shown that each inlet pipe 38 comprises the elbow38a communicating with the inlet belt of the front cylinder and a T 38hcommunicating with the inlet ports of the rear cylinder and connected tothe elbow 44 of a scavenging blower or supercharger 46 which is providedwith an impeller 48 driven at high speed thru gearing (not shown) andhaving an air inlet duct 50, better seen in Figure 1. The exhaust pipes40 similarlyinclude elbows 40a communicating with exhaust ports of thefront cylinders and Ts 40h communicating with exhaust ports of the rearcylinders and provided with outlet lpipes 40e. In Figure 3 a propeller52 has been shown as secured to the crankshaft 22.

Referring again to Figure 1, it will be seen that counterweights 54 and58 disposed Aat 180 to each other are secured at opposite ends of thecrankshaft bywhiclr means the rotating couple characteristics of angularcrankpin or wabble plate engines may be completely balanced.

It will also be seen that the cylinder disposition of this invention isapplicable to two-cycle operation with any known means for preparing thefuel charge.

Regardless of the fuel system used, this invention provides an extremelycompact engine having paired cylinders for two cycle operation, thusrealizing the good scavenging characteristics of the widely separatedinlet and exhaust ports, while it achieves at the same time good balanceand even spacing of the firing impulses in combination with theout-of-phase piston motion desired for the proper timing of the inletand exhaust ports.

While I have described my invention in detail in its present preferredembodiment, it will be obvious to those skilled in the art afterunderstanding my invention, that various changes and modifications maybe made therein without departing from the spirit or scope thereof. Iaim in the appended claims to cover all such modifications and changes.

What is claimed is:

1. In an engine, in combination, a power shaft, a plurality of cylindersunited in pairs by common combustion chambers at each end of the engineand arranged around and parallel to the power shaft, the circumferentialspacing of adjacent cylinders between pairs being greater than thespacing of the cylinders of a pair, one cylinder of each pair havinginlet ports and the other cylinder of each pair having exhaust ports,double-ended pistons working in said cylinders and adapted to overrunsaid ports in said cylinders, and pipes connected to said ports anddisposed in the spaces between adjacent pairs of cylinders substantiallywithin the overall diameter of the engine.`

2. In an engine, in combination, a power shaft, a plurality of cylindersunited in pairs by cornmon combustion chambers arranged around andparallel to the power shaft, the circumferential spacing of adjacentcylinders between pairs being greater than the spacing of the cylindersof a pair, one cylinder of each pair having inlet ports and the othercylinder of each pair having exhaust ports, pistons working in saidcylinders and adapted to overrun said ports, and intake and exhaustmanifolds connected to the respective ports and disposed in the spacesbetween adjacent pairs of cylinders substantially within the overalldiameter of theengine.

3. The combination, in an internal combustion engine, of a power shaft,a casing within which said power shaft is enclosed and beyond one end ofwhich said power shaft extends, a plurality of cylinders within saidcasing, said cylinders being united in pairs by common combustionchambers and being arranged around and in parallelism with said powershaft, the circumferential spacing of adjacent cylinders between pairsbeing greater than the spacing of the cylinders of a pair, one cylinderof each pair having inlet ports and the other cylinder of each pairhaving exhaust ports, pistons operating within said cylinders to overrunsaid ports, a supercharger fastened to said casing at that end thereofwithin which the common combustion chambers are formed, and intake andexhaust manifolds iitted in the spaces between adjacent pairs ofcylinders substantially within the overall diameter of the engine, saidmanifolds being open respectively to said supercharger and to the intakeports on the one hand and to the exhaust ports on the other.

4. In an internal lcombustion engine. a power gether, said bolts beingdisposed circumferentially about said power shaft, `and one said casingsection having formed vtherein a recess, and a counter weight fastenedto said power shaft and rotatable within said recess.

ROLAND CHILTON.

